src/thttpd-2.27/timers.c

   1 /* timers.c - simple timer routines
   2 **
   3 ** Copyright © 1995,1998,2000,2014 by Jef Poskanzer <jef@mail.acme.com>.
   4 ** All rights reserved.
   5 **
   6 ** Redistribution and use in source and binary forms, with or without
   7 ** modification, are permitted provided that the following conditions
   8 ** are met:
   9 ** 1. Redistributions of source code must retain the above copyright
  10 **    notice, this list of conditions and the following disclaimer.
  11 ** 2. Redistributions in binary form must reproduce the above copyright
  12 **    notice, this list of conditions and the following disclaimer in the
  13 **    documentation and/or other materials provided with the distribution.
  14 **
  15 ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18 ** ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25 ** SUCH DAMAGE.
  26 */
  27
  28 #include <sys/types.h>
  29
  30 #include <stdlib.h>
  31 #include <stdio.h>
  32 #include <syslog.h>
  33
  34 #include "timers.h"
  35
  36
  37 #define HASH_SIZE 67
  38 static Timer* timers[HASH_SIZE];
  39 static Timer* free_timers;
  40 static int alloc_count, active_count, free_count;
  41
  42 ClientData JunkClientData;
  43
  44
  45
  46 static unsigned int
  47 hash( Timer* t )
  48     {
  49     /* We can hash on the trigger time, even though it can change over
  50     ** the life of a timer via either the periodic bit or the tmr_reset()
  51     ** call.  This is because both of those guys call l_resort(), which
  52     ** recomputes the hash and moves the timer to the appropriate list.
  53     */
  54     return (
  55         (unsigned int) t->time.tv_sec ^
  56         (unsigned int) t->time.tv_usec ) % HASH_SIZE;
  57     }
  58
  59
  60 static void
  61 l_add( Timer* t )
  62     {
  63     int h = t->hash;
  64     Timer* t2;
  65     Timer* t2prev;
  66
  67     t2 = timers[h];
  68     if ( t2 == (Timer*) 0 )
  69         {
  70         /* The list is empty. */
  71         timers[h] = t;
  72         t->prev = t->next = (Timer*) 0;
  73         }
  74     else
  75         {
  76         if ( t->time.tv_sec < t2->time.tv_sec ||
  77              ( t->time.tv_sec == t2->time.tv_sec &&
  78                t->time.tv_usec <= t2->time.tv_usec ) )
  79             {
  80             /* The new timer goes at the head of the list. */
  81             timers[h] = t;
  82             t->prev = (Timer*) 0;
  83             t->next = t2;
  84             t2->prev = t;
  85             }
  86         else
  87             {
  88             /* Walk the list to find the insertion point. */
  89             for ( t2prev = t2, t2 = t2->next; t2 != (Timer*) 0;
  90                   t2prev = t2, t2 = t2->next )
  91                 {
  92                 if ( t->time.tv_sec < t2->time.tv_sec ||
  93                      ( t->time.tv_sec == t2->time.tv_sec &&
  94                        t->time.tv_usec <= t2->time.tv_usec ) )
  95                     {
  96                     /* Found it. */
  97                     t2prev->next = t;
  98                     t->prev = t2prev;
  99                     t->next = t2;
 100                     t2->prev = t;
 101                     return;
 102                     }
 103                 }
 104             /* Oops, got to the end of the list.  Add to tail. */
 105             t2prev->next = t;
 106             t->prev = t2prev;
 107             t->next = (Timer*) 0;
 108             }
 109         }
 110     }
 111
 112
 113 static void
 114 l_remove( Timer* t )
 115     {
 116     int h = t->hash;
 117
 118     if ( t->prev == (Timer*) 0 )
 119         timers[h] = t->next;
 120     else
 121         t->prev->next = t->next;
 122     if ( t->next != (Timer*) 0 )
 123         t->next->prev = t->prev;
 124     }
 125
 126
 127 static void
 128 l_resort( Timer* t )
 129     {
 130     /* Remove the timer from its old list. */
 131     l_remove( t );
 132     /* Recompute the hash. */
 133     t->hash = hash( t );
 134     /* And add it back in to its new list, sorted correctly. */
 135     l_add( t );
 136     }
 137
 138
 139 void
 140 tmr_init( void )
 141     {
 142     int h;
 143
 144     for ( h = 0; h < HASH_SIZE; ++h )
 145         timers[h] = (Timer*) 0;
 146     free_timers = (Timer*) 0;
 147     alloc_count = active_count = free_count = 0;
 148     }
 149
 150
 151 Timer*
 152 tmr_create(
 153     struct timeval* nowP, TimerProc* timer_proc, ClientData client_data,
 154     long msecs, int periodic )
 155     {
 156     Timer* t;
 157
 158     if ( free_timers != (Timer*) 0 )
 159         {
 160         t = free_timers;
 161         free_timers = t->next;
 162         --free_count;
 163         }
 164     else
 165         {
 166         t = (Timer*) malloc( sizeof(Timer) );
 167         if ( t == (Timer*) 0 )
 168             return (Timer*) 0;
 169         ++alloc_count;
 170         }
 171
 172     t->timer_proc = timer_proc;
 173     t->client_data = client_data;
 174     t->msecs = msecs;
 175     t->periodic = periodic;
 176     if ( nowP != (struct timeval*) 0 )
 177         t->time = *nowP;
 178     else
 179         (void) gettimeofday( &t->time, (struct timezone*) 0 );
 180     t->time.tv_sec += msecs / 1000L;
 181     t->time.tv_usec += ( msecs % 1000L ) * 1000L;
 182     if ( t->time.tv_usec >= 1000000L )
 183         {
 184         t->time.tv_sec += t->time.tv_usec / 1000000L;
 185         t->time.tv_usec %= 1000000L;
 186         }
 187     t->hash = hash( t );
 188     /* Add the new timer to the proper active list. */
 189     l_add( t );
 190     ++active_count;
 191
 192     return t;
 193     }
 194
 195
 196 struct timeval*
 197 tmr_timeout( struct timeval* nowP )
 198     {
 199     long msecs;
 200     static struct timeval timeout;
 201
 202     msecs = tmr_mstimeout( nowP );
 203     if ( msecs == INFTIM )
 204         return (struct timeval*) 0;
 205     timeout.tv_sec = msecs / 1000L;
 206     timeout.tv_usec = ( msecs % 1000L ) * 1000L;
 207     return &timeout;
 208     }
 209
 210
 211 long
 212 tmr_mstimeout( struct timeval* nowP )
 213     {
 214     int h;
 215     int gotone;
 216     long msecs, m;
 217     Timer* t;
 218
 219     gotone = 0;
 220     msecs = 0;          /* make lint happy */
 221     /* Since the lists are sorted, we only need to look at the
 222     ** first timer on each one.
 223     */
 224     for ( h = 0; h < HASH_SIZE; ++h )
 225         {
 226         t = timers[h];
 227         if ( t != (Timer*) 0 )
 228             {
 229             m = ( t->time.tv_sec - nowP->tv_sec ) * 1000L +
 230                 ( t->time.tv_usec - nowP->tv_usec ) / 1000L;
 231             if ( ! gotone )
 232                 {
 233                 msecs = m;
 234                 gotone = 1;
 235                 }
 236             else if ( m < msecs )
 237                 msecs = m;
 238             }
 239         }
 240     if ( ! gotone )
 241         return INFTIM;
 242     if ( msecs <= 0 )
 243         msecs = 0;
 244     return msecs;
 245     }
 246
 247
 248 void
 249 tmr_run( struct timeval* nowP )
 250     {
 251     int h;
 252     Timer* t;
 253     Timer* next;
 254
 255     for ( h = 0; h < HASH_SIZE; ++h )
 256         for ( t = timers[h]; t != (Timer*) 0; t = next )
 257             {
 258             next = t->next;
 259             /* Since the lists are sorted, as soon as we find a timer
 260             ** that isn't ready yet, we can go on to the next list.
 261             */
 262             if ( t->time.tv_sec > nowP->tv_sec ||
 263                  ( t->time.tv_sec == nowP->tv_sec &&
 264                    t->time.tv_usec > nowP->tv_usec ) )
 265                 break;
 266             (t->timer_proc)( t->client_data, nowP );
 267             if ( t->periodic )
 268                 {
 269                 /* Reschedule. */
 270                 t->time.tv_sec += t->msecs / 1000L;
 271                 t->time.tv_usec += ( t->msecs % 1000L ) * 1000L;
 272                 if ( t->time.tv_usec >= 1000000L )
 273                     {
 274                     t->time.tv_sec += t->time.tv_usec / 1000000L;
 275                     t->time.tv_usec %= 1000000L;
 276                     }
 277                 l_resort( t );
 278                 }
 279             else
 280                 tmr_cancel( t );
 281             }
 282     }
 283
 284
 285 void
 286 tmr_reset( struct timeval* nowP, Timer* t )
 287     {
 288     t->time = *nowP;
 289     t->time.tv_sec += t->msecs / 1000L;
 290     t->time.tv_usec += ( t->msecs % 1000L ) * 1000L;
 291     if ( t->time.tv_usec >= 1000000L )
 292         {
 293         t->time.tv_sec += t->time.tv_usec / 1000000L;
 294         t->time.tv_usec %= 1000000L;
 295         }
 296     l_resort( t );
 297     }
 298
 299
 300 void
 301 tmr_cancel( Timer* t )
 302     {
 303     /* Remove it from its active list. */
 304     l_remove( t );
 305     --active_count;
 306     /* And put it on the free list. */
 307     t->next = free_timers;
 308     free_timers = t;
 309     ++free_count;
 310     t->prev = (Timer*) 0;
 311     }
 312
 313
 314 void
 315 tmr_cleanup( void )
 316     {
 317     Timer* t;
 318
 319     while ( free_timers != (Timer*) 0 )
 320         {
 321         t = free_timers;
 322         free_timers = t->next;
 323         --free_count;
 324         free( (void*) t );
 325         --alloc_count;
 326         }
 327     }
 328
 329
 330 void
 331 tmr_term( void )
 332     {
 333     int h;
 334
 335     for ( h = 0; h < HASH_SIZE; ++h )
 336         while ( timers[h] != (Timer*) 0 )
 337             tmr_cancel( timers[h] );
 338     tmr_cleanup();
 339     }
 340
 341
 342 /* Generate debugging statistics syslog message. */
 343 void
 344 tmr_logstats( long secs )
 345     {
 346     syslog(
 347         LOG_NOTICE, "  timers - %d allocated, %d active, %d free",
 348         alloc_count, active_count, free_count );
 349     if ( active_count + free_count != alloc_count )
 350         syslog( LOG_ERR, "timer counts don't add up!" );
 351     }